WELCOME to YT.
I would get to the vet ASAP. This pup is very young, and
extremely vulnerable - and will be for quite awhile. I would recommend you post in the breeder's section right away and ask for help on how to care for this puppy who should truly still be with its Mother. There is a puppy gruel recipe somewhere, which I think you'll need. You'll need to feed frequently in the day and may need to get up during the night for a while. You should buy Nutrical right away (Petsmart/Petco).
I would not be allowing any shots for quite awhile - the vet should know this as well. But if they try to push shots, refuse. Puppy is too fragile.
I really cannot express how fragile this puppy is at this age - so I'd really encourage you to gather info here - and to get to a vet asap. BEST OF LUCK.